This invention relates to landing gear for trailers and the like, more particularly, a landing gear assembly having a quick to ground feature and increased structural stability.
Vehicles, such as a recreational vehicle or semi-trailer, incorporate jacks to support, level, or raise the vehicle. Semi-truck trailers utilize jacks as landing gear legs in a landing gear assembly to raise and support the front of the trailer when disengaged from a semi-truck tractor.
In particular, a typical semi-truck tractor and trailer are attached utilizing a xe2x80x9cfifth wheelxe2x80x9d type connection. A fifth wheel connection has a lubricated flat swivel plate and catch assembly mounted on the semi-truck tractor to engage a corresponding lubricated flat swivel plate and downwardly protruding xe2x80x9cking pinxe2x80x9d mounted on the underside of the forward portion of the trailer. The trailer king pin is received in a slot in the tractor swivel plate where it engages the tractor catch assembly locking the tractor and trailer together.
In order to disengage the tractor from the trailer, landing gear legs mounted on a forward section of the trailer are extended to the ground raising the king pin upwardly disengaging it from the catch assembly. Upon disengagement, the tractor pulls away from the trailer which is now supported by trailer rear wheels and the landing gear.
Typical landing gear, such as disclosed in U.S. Pat. No. 4,307,896, are formed with intermitting box-section supporting legs. In U.S. Pat. No. 4,307,896, the interfitting box-sections have a ground engaging leg telescopically interfitted with a box-like fixed leg which is mounted to the trailer. The ground engaging leg telescopes between a retracted position and an extended position. Typically the ground engaging leg is manually or electrically driven in the telescoping direction. Landing gear having a single telescoping section, however, is time consuming to extend and retract because the single telescoping section must be driven the entire distance of extension or retraction.
In order to reduce the time required to extend or retract the landing gear legs, a three piece telescoping leg was developed with a quick to ground feature. In the three piece leg with a quick to ground feature, the leg has an outer member, a middle member telescoping from the outer member, and an inner member telescoping from the middle member. The inner member telescopes freely from the middle member to engage the ground and is then locked into a fixed relationship with the middle member. The middle member is then manually or electrically driven to raise the semi trailer. This configuration deploys the inner member having the smallest cross section, and therefore the least structural stability, to engage the ground and support the trailer.
The present invention provides a landing gear leg adapted for mounting to a vehicle having an outer member, and a middle member telescoped slidably into the outer member. The middle member has a first end and a second end. The first end extends beyond the outer member. An inner member telescoped slidably into the middle member has a first end positioned within the outer member and a second end extending beyond the outer member. A locking mechanism locks the middle member in a fixed relationship with the inner member, and a drive mechanism slidably drives the inner member in relationship with the outer member from a retracted position to an extended position.
A general objective of the present invention is to provide a quick to ground landing gear with improved structural stability. This objective is accomplished by providing a middle member slidably telescoping from an outer member and an inner member slidably telescoping from the middle member, wherein the middle member telescopes from said outer member for engaging the ground and is locked in a fixed relationship with the inner member which is driven by a drive mechanism for further extension of the leg.
Another objective of the present invention is to provide a landing gear assembly with improved structural stability. This objective is accomplished by providing a pair of landing gear legs having improved structural stability in which leg inner members are substantially simultaneously driven for further extension of the leg.
Still another objective of the present invention is to provide a method of extending a landing gear leg with improved structural stability. This is accomplished by telescoping a landing gear leg middle member slidably inserted inside a landing gear leg outer member from a retracted position to an extended position; fixing the landing gear leg middle member in relationship with a landing gear leg inner member slidably inserted inside the landing gear leg middle member; and driving the landing gear leg inner member from a retracted position to an extended position.
Yet another objective of the present invention is to provide a landing gear leg with a simple drive mechanism. This is accomplished by providing a rack and pinion drive mechanism.